WO2019119394A1

WO2019119394A1 - Techniques for prioritizing frequency channels for reselection in wireless communications

Info

Publication number: WO2019119394A1
Application number: PCT/CN2017/117913
Authority: WO
Inventors: Guibing GU; Ankur Srivastava; Miao Fu; Shiau-He Tsai; Ling Hang; Aimin SHANG; Yongrui PENG; Kishore Kumar YANNAKULA
Original assignee: Qualcomm Incorporated
Priority date: 2017-12-22
Filing date: 2017-12-22
Publication date: 2019-06-27

Abstract

Aspects of the present disclosure describe prioritizing frequency channels for measuring in reselection. It can be determined whether one or more frequency channels received in a list of individually prioritized frequency channels are valid. If so, the one or more frequency channels determined to be valid can be added to a reselection set of priorities. If not, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, can be added to the reselection set of priorities. Where the reselection set of priorities includes at least one frequency channel, a target cell can be searched for reselection on the at least one frequency channel in the reselection set of priorities.

Description

TECHNIQUES FOR PRIORITIZING FREQUENCY CHANNELS FOR RESELECTION IN WIRELESS COMMUNICATIONS

BACKGROUND

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to prioritizing frequency channel measurement in wireless communications.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. For example, fourth generating (4G) and/or fifth generation (5G) wireless communications technologies have been, or are being, developed to expand and support diverse usage scenarios and applications with respect to current mobile network generations. An example of a 4G network can include a third generation partnership project (3GPP) long term evolution (LTE) network.

In LTE networks, user equipment (UE) can reselect to networks of other technologies, which may include legacy Global System for Mobile Communications (GSM) technologies, in certain detectable situations. For example, where radio frequency (RF) conditions of a UE on a current LTE cell are weak (e.g., signal strength falls below a threshold) or for purposes of load balancing, etc., the LTE cell can cause the UE to reselect to another network, which may include a GSM network. For example, the UE can measure cells on frequency channels according to a configured list of frequency channels, which may be generated based on multiple received lists of frequency channels, to detect the GSM cell. Due to differences in received lists of frequency channels, however, it is possible that a UE may stay connected to the GSM cell though more desirable cells (e.g., an LTE cell) may be available for reselection.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

According to an example, a method for prioritizing frequency channels for measuring in reselection is provided. The method includes determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid, adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities, adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities, and where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.

In another example, an apparatus for wireless communication is provided that includes a transceiver for communicating in a wireless network via one or more antennas, a memory configured to store instructions, and one or more processors communicatively coupled with the transceiver and the memory. The one or more processors are configured to determine whether one or more frequency channels received in a list of individually prioritized frequency channels are valid, add, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities, add, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities, and where the reselection set of priorities includes at least one frequency channel, search for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.

In yet another example, an apparatus for prioritizing frequency channels for measuring in reselection is provided. The apparatus includes means for determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid, means for adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities, means for adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities, and means for, where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.

In another example, a computer-readable medium including code executable by one or more processors for prioritizing frequency channels for measuring in reselection is provided. The code includes code for determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid, code for adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities, code for adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities, and code for, where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements, and in which:

FIG. 1 illustrates an example of a wireless communication system, in accordance with various aspects of the present disclosure;

FIG. 2 is a block diagram illustrating an example of a UE, in accordance with various aspects of the present disclosure;

FIG. 3 is a flow chart illustrating an example of a method for prioritizing frequency channels in reselection, in accordance with various aspects of the present disclosure; and

FIG. 4 is a block diagram illustrating an example of a MIMO communication system including a base station and a UE, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect (s) may be practiced without these specific details.

The described features generally relate to determining frequency channel priorities for cell reselection where different lists of frequency channel priorities are received. For example, some wireless communication technologies, such as third generation partnership project (3GPP) long term evolution (LTE) , enable cells to configure common priority lists of frequency channels to user equipment (UE) communicating with the cells and individual priority lists of frequency channels (e.g., individual for each UE) . The UE can generate a reselection priority list (e.g., based on the individual priority list or the common priority list) according to certain rules where some frequency channels in the generated reselection priority list may not be considered. For example, in LTE, a UE can consider a set (e.g., list) of individual priorities as valid if it includes at least one priority. In this example, the UE can consider a set (e.g., list) of common priorities may be valid if the set of priorities includes a priority for a GSM EDGE Radio Access Network (GERAN) and if the UE does not have a valid set of individual priorities.

In this specific example, it is possible that the UE ends up with a reselection priority list that includes only the individual priorities, which may have undesirable results where the UE reselects from LTE (e.g., from the frequency channel corresponding to the individual priority) to GSM (e.g., due to poor RF conditions, load balancing, etc. ) . In this case, the UE may stay in GSM though there may be more desirable LTE cells available. For example, in radio resource control connection (RRC) release, the LTE cell may have provisioned an individual priority list to the UE (or at another time) ; thus, the UE can have a valid individual priority list. In this regard, regardless of whether the UE has also received a common priority list, the generated reselection priority list only includes the frequency channel (s) in the individual priority list, and the UE performs cell measurements only on the frequency channels in the individual priority list based on the LTE functionality described above. In some cases, LTE may also include an override for the individual and common priority lists; this case may assume this override does not exist, or otherwise does not relate to a frequency on which an LTE cell can be found.

Aspects described herein relate to managing priority lists to more effectively handle situations where the UE reselects to a less desirable radio access technology (RAT) . For example, where the UE receives an individual priority list and determines the individual priorities in this list to be valid, the individual priorities and corresponding frequency channels in this list can be added to the generated reselection priority list regardless of any received list of common priorities. In this example, where the individual priorities are not valid, any common priorities received in a list of common priorities, and corresponding frequency channels, can be added to the generated reselection priority list. The UE can attempt to measure cells of the more desirable RAT for reselection thereto using the frequency channels includes in the generated reselection priority list (e.g., according to a priority of the frequency channels specified in the list) . If a cell is not found (or if there are no frequency channels in the generated priority list –e.g., no valid priorities between the individual and common priorities) , the UE can attempt a search for another cell as defined at least partially by a home public land mobile network (HPLMN) . In any case, the UE may be able to more quickly identify a cell of the more desirable RAT (e.g., LTE) for reselection thereto, which may be desirable in static or low speed movement scenarios.

The described features will be presented in more detail below with reference to FIGS. 1-4.

As used in this application, the terms “component, ” “module, ” “system” and the like are intended to include a computer-related entity, such as but not limited to hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets, such as data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal.

Techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and “network” may often be used interchangeably. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) , etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD) , etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) , Evolved UTRA (E-UTRA) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM ^TM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to 5G networks or other next generation communication systems) .

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in other examples.

Various aspects or features will be presented in terms of systems that can include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems can include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. A combination of these approaches can also be used.

FIG. 1 illustrates an example of a wireless communication system 100 in accordance with various aspects of the present disclosure. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. The core network 130 may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., S1, etc. ) . The base stations 105 may perform radio configuration and scheduling for communication with the UEs 115, or may operate under the control of a base station controller (not shown) . In various examples, the base stations 105 may communicate, either directly or indirectly (e.g., through core network 130) , with one another over backhaul links 134 (e.g., X2, etc. ) , which may be wired or wireless communication links.

The base stations 105 may wirelessly communicate with the UEs 115 via one or more base station antennas. Each of the base stations 105 may provide communication coverage for a respective geographic coverage area 110. In some examples, base stations 105 may be referred to as a network entity, a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB) , Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area 110 for a base station 105 may be divided into sectors making up only a portion of the coverage area (not shown) . The wireless communication system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . There may be overlapping geographic coverage areas 110 for different technologies.

In some examples, the wireless communication system 100 may be or include a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) network. The wireless communication system 100 may also be a next generation network, such as a 5G wireless communication network. In LTE/LTE-A networks, the term evolved node B (eNB) , gNB, etc. may be generally used to describe the base stations 105, while the term UE may be generally used to describe the UEs 115. The wireless communication system 100 may be a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station 105 may provide communication coverage for a macro cell, a small cell, or other types of cell. The term “cell” is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc. ) of a carrier or base station, depending on context.

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscriptions with the network provider.

A small cell may include a lower-powered base station, as compared with a macro cell, that may operate in the same or different (e.g., licensed, unlicensed, etc. ) frequency bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by UEs 115 having an association with the femto cell (e.g., UEs 115 in a closed subscriber group (CSG) , UEs 115 for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB, gNB, etc. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers) .

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A packet data convergence protocol (PDCP) layer can provide header compression, ciphering, integrity protection, etc. of IP packets. A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A media access control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use HARQ to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and the base stations 105. The RRC protocol layer may also be used for core network 130 support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be stationary or mobile. A UE 115 may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE 115 may be a cellular phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, an entertainment device, a vehicular component, or the like. A UE may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

The communication links 125 shown in wireless communication system 100 may carry UL transmissions from a UE 115 to a base station 105, or downlink (DL) transmissions, from a base station 105 to a UE 115. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each communication link 125 may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc. ) , overhead information, user data, etc. The communication links 125 may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources) . Frame structures may be defined for FDD (e.g., frame structure type 1) and TDD (e.g., frame structure type 2) .

In aspects of the wireless communication system 100, base stations 105 or UEs 115 may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations 105 and UEs 115. Additionally or alternatively, base stations 105 or UEs 115 may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication system 100 may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC) , a layer, a channel, etc. The terms “carrier, ” “component carrier, ” “cell, ” and “channel” may be used interchangeably herein. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers.

In aspects of the wireless communication system 100, one or more of the base stations 105 may include functionality for providing priority lists of frequency channels to one or more UEs. For example, a base station may communicate a common priority list to a UE 115 in a broadcast message (e.g., system information broadcast (SIB) ) and/or an individual priority list to the UE 115 in a RRC message (e.g., RRC Connection Release or other message) . UE 115 can include a communicating component 240 for receiving the priority lists and generating a reselection priority list for measuring frequency channels for cells to which to perform reselection. As described further herein, the communicating component 240 may, at least in some cases, generate the reselection priority list to include priorities from an individual priority list, if valid, or frequencies from the common priority list, if the individual priorities are not valid, which may improve the likelihood of discovering a cell for reselection. In addition, for example, the communicating component 240 may perform a HPLMN reselection (or other reselection) procedure where no valid priorities are present and/or where a cell is not otherwise discovered.

Turning now to FIGS. 2-4, aspects are depicted with reference to one or more components and one or more methods that may perform the actions or operations described herein, where aspects in dashed line may be optional. Although the operations described below in FIG. 3 are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Moreover, it should be understood that the following actions, functions, and/or described components may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component capable of performing the described actions or functions.

Referring to FIG. 2, a block diagram 200 is shown that includes a portion of a wireless communications system having multiple UEs 115 in communication with a base station 105 via communication links 125, where the base station 105 is also connected to a network 210, which may include one or more components of a core network (e.g., core network 130) . The UEs 115 may be examples of the UEs described in the present disclosure that are configured to detect fake cells.

In an aspect, the UE 115 in FIG. 2 may include one or more processors 205 and/or memory 202 that may operate in combination with a communicating component 240 to perform the functions, methods (e.g., method 300 of FIG. 3) , etc., presented in the present disclosure. In accordance with the present disclosure, the communicating component 240 may include one or more components for determining priorities of frequency channels in measuring for cells in reselection. For example, communicating component 240 may include a priority determining component 242 for determining one or more sets of priorities received from a base station 105 and/or accordingly determining a reselection set of priorities of frequency channels to measure in cell reselection, a cell measuring component 244 for measuring one or more cells based on the reselection set of priorities, and/or a cell reselecting component 246 for performing cell reselection to one or more cells discovered on one or more of the measured frequency channels.

The one or more processors 205 may include a modem 220 that uses one or more modem processors. The various functions related to the communicating component 240, and/or its sub-components, may be included in modem 220 and/or processor 205 and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors 205 may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a transceiver processor associated with transceiver 270, or a system-on-chip (SoC) . In particular, the one or more processors 205 may execute functions and components included in the communicating component 240. In another example, communicating component 240, or sub-components thereof, may operate at one or more communication layers, such as physical layer or L1, MAC layer or L2, a PDCP/RLC layer or L3, etc., to prioritize frequency channels and accordingly measure for cells on the frequency channels in performing reselection.

In some examples, the communicating component 240 and each of the sub-components may comprise hardware, firmware, and/or software and may be configured to execute code or perform instructions stored in a memory (e.g., a computer-readable storage medium, such as memory 202 discussed below) . Moreover, in an aspect, the UE 115 in FIG. 2 may include an RF front end 290 and transceiver 270 for receiving and transmitting radio transmissions to, for example, base stations 105. The transceiver 270 may coordinate with the modem 220 to receive signals that include packets (e.g., and/or one or more related PDUs) . RF front end 290 may be connected to one or more antennas 273 and can include one or more switches 292, one or more amplifiers (e.g., PAs 294 and/or LNAs 291) , and one or more filters 293 for transmitting and receiving RF signals on uplink channels and downlink channels. In an aspect, the components of the RF front end 290 can connect with transceiver 270. The transceiver 270 may connect to one or more of modem 220 and processors 205.

The transceiver 270 may be configured to transmit (e.g., via transmitter (TX) radio 275) and receive (e.g., via receiver (RX) radio 280) wireless signals through antennas 273 via the RF front end 290. In an aspect, the transceiver 270 may be tuned to operate at specified frequencies such that the UE 115 can communicate with, for example, base stations 105. In an aspect, for example, the modem 220 can configure the transceiver 270 to operate at a specified frequency and power level based on the configuration of the UE 115 and communication protocol used by the modem 220.

The UE 115 in FIG. 2 may further include a memory 202, such as for storing data used herein and/or local versions of applications or communicating component 240 and/or one or more of its sub-components being executed by processor 205. Memory 202 can include any type of computer-readable medium usable by a computer or processor 205, such as RAM, ROM, tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory 202 may be a computer-readable storage medium that stores one or more computer-executable codes defining communicating component 240 and/or one or more of its sub-components. Additionally or alternatively, the UE 115 may include a bus 211 for coupling one or more of the RF front end 290, the transceiver 274, the memory 202, or the processor 205, and to exchange signaling information between each of the components and/or sub-components of the UE 115.

In an aspect, the processor (s) 205 may correspond to one or more of the processors described in connection with the UE 115 in FIG. 4. Similarly, the memory 202 may correspond to the memory described in connection with the UE 115 in FIG. 4.

FIG. 3 illustrates a flow chart of an example of a method 300 for determining (e.g., by a UE) a reselection set of priorities for performing cell measurements in reselection (e.g., inter-RAT (IRAT) reselection) .

At Block 302, a set of common priorities can be received. In an aspect, communicating component 240, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can receive the set of common priorities. For example, communicating component 240 can receive the set of common priorities from base station 105 in a broadcast message, such as one or more SIBs. For example, the set of common priorities may include common priorities information received in a system information type 2quater, PLMN-specific UTRAN and E-UTRAN common priorities, etc., as defined in 3GPP Technical Specification (TS) 44.018. The set of common priorities can include a list of one or more frequency channels and associated priorities, where the priority can be an integer representing relative priority. In this regard, the UE 115 can determine a priority for measuring frequency channels for cells during reselection, where the priority can be determined based on the integer (e.g., frequency channels with a higher indicated priority integer in the set of common priorities can be measured first) . Moreover, for example, the set of common priorities, as received, may indicate the frequency channels using an E-UTRA Absolute Radio Frequency Channel Number (EARFCN) .

At Block 304, a set of individual priorities can be received. In an aspect, communicating component 240, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can receive the set of individual priorities. For example, communicating component 240 can receive the set of individual priorities from base station 105 in a dedicated message, such as a RRC message (e.g., which may include a channel release message, packet measurement order message, packet cell change order message, etc., as defined in 3GPP TS 44.018) . The set of individual priorities can include a list of one or more frequency channels and associated priorities, where the priority can be an integer representing relative priority. Moreover, for example, the set of individual priorities, as received, may indicate the frequency channels using an EARFCN as well. Where the UE 115 also receives the set of individual priorities, for example, the UE 115 can determine a priority for measuring frequency channels for cells during reselection based additionally on the individual priorities.

For example, in LTE, the UE 115 can generally prefer the frequency channels in the individual priorities over those in the common priorities. For example, when the UE 115 is communicating with an LTE cell, the LTE cell may cause the UE 115 to reselect to another LTE cell or fallback to a GSM cell, which can be based on RF conditions of the connection between the UE 115 and the LTE cell, load balancing considerations on the LTE cell, etc. In this example, the LTE cell (e.g., via base station 105) may provide the UE 115 with a set of individual priorities in a RRC Connection Release message. For example, this set of individual priorities may include one or more frequency channels associated with the LTE cell to cause the UE 115 to prioritize the frequency channels and possibly reconnect to the LTE cell when conditions improve, or may include frequency channels of neighboring LTE cells to cause the UE 115 to prioritize these frequency channels for purposes of load balancing among LTE cells. As described above, the UE 115, at least in some cases, may only consider the individual priorities in measuring frequency channels for reselection.

For example, 3GPP TS 44.018 states that a set of individual priorities is valid if it contains at least one priority, and that a set of common priorities is valid if both of the following conditions are met: the set of priorities includes a priority for GERAN; and the mobile station does not have a valid set of individual priorities. Thus, a UE operating according to these specifications may measure only the frequency channels in the received set of individual priorities, where the individual priorities are valid, though other LTE cells may be present and connection thereto may be preferable (e.g., especially where the UE 115 is unable to connect to the previous LTE cell and may remain connected to the GSM cell for a long period of time) . In this regard, the set of individual priorities (e.g., or the corresponding individually prioritized frequency channels) can be specified such to override the set of common priorities (e.g., or the corresponding commonly prioritized frequency channels) .

This can be possible in other examples as well, such as where the UE 115 moves from GSM back to LTE, from LTE to WCDMA, from LTE to GSM, to WCDMA, etc. In any case, a set of dedicated priorities received by the UE 115 on one cell may not be valid on another cell to which the UE 115 reselected in IRAT reselection, and thus may cause the UE 115 to not measure other frequency channels (e.g., as specified in a set of common priorities) though neighboring cells may be available for reselection on those frequency channels. Aspects described further herein attempt to avoid this case and allow the UE 115 to measure other frequency channels (e.g., in the set of common priorities) to possibly find other LTE (or other desirable) cells that may not use frequency channels in the set of individual priorities.

At Block 306, it can be determined whether the individual priorities are valid. In an aspect, priority determining component 242, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, etc., can determine whether the individual priorities are valid. For example, priority determining component 242 can determine whether the individual priorities (e.g. frequency channels corresponding to the individual priorities) are valid based at least in part on determining whether a priority is available for the specified channel frequency. For example, the UE 115 may reselect from one cell to another and may inherit the individual priorities from the previous cell. These individual priorities, however, may not be valid with the current cell. In a specific example, as described above, the UE 115 may receive the set of individual priorities from an LTE cell and may reselect to a GSM cell. In this example, the individual priorities received from the LTE cell (e.g., in a RRC connection release message) may not be valid for the GSM cell, which may hinder the ability to measure corresponding frequency channels for target LTE cells in IRAT reselection.

Where the individual priorities are valid at Block 306, at Block 308, the individual priorities can be added to a reselection set of priorities. In an aspect, priority determining component 242, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, etc., can add the individual priorities to the reselection set of priorities. For example, priority determining component 242 can add the frequency channels and associated priorities (e.g., integer values) from the individual set of priorities to the reselection set of priorities for use in measuring cells for reselection. This can occur regardless of the set of common priorities, in one example.

Where the individual priorities are not valid at Block 306, at Block 310, the common priorities (e.g. frequency channels corresponding to the common priorities) can be added to a reselection set of priorities. In an aspect, priority determining component 242, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, etc., can add the common priorities to the reselection set of priorities. For example, priority determining component 242 can add the frequency channels and associated priorities (e.g., integer values) from the common set of priorities to the reselection set of priorities for use in measuring cells for reselection.

In either case, at Block 312, it can be determined whether the reselection set of priorities (e.g. frequency channels corresponding to the set of priorities) includes a valid priority. In an aspect, priority determining component 242, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, etc., can determine whether the reselection set of priorities includes a valid priority (e.g., at least one valid priority) . As described, for example, the individual priorities inherited from the LTE cell may not have included a valid priority. The common priorities received from the LTE cell may also not have included a valid priority for the GSM cell (or WCDMA cell, etc. ) , in one example.

Where the reselection set of priorities includes a valid priority at Block 312, at Block 314, a target cell can be searched for on at least one frequency channel in the reselection set of priorities. In an aspect, cell measuring component 244, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, priority determining component 242, etc., can search for the target cell on the at least one frequency channel in the reselection set of priorities. For example, cell measuring component 244 can measure signal strength received from cells on the at least one frequency channel, and can evaluate one or more frequency channels in the set of priorities based on the relative priority associated with the frequency channel until a cell of suitable signal strength and/or desired RAT is discovered.

Optionally, if the target cell is discovered at Block 316, a reselection procedure can be performed at Block 318 to reselect to the target cell. In an aspect, cell reselecting component 246, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, priority determining component 242, cell measuring component 244, etc., can determine whether the target cell is discovered and can accordingly perform the reselection procedure to the target cell.

Where the reselection set of priorities does not include a valid priority at Block 312, or where a cell is not discovered at Block 316 (e.g., after measuring at least one or all of the frequency channels in the reselection set of priorities) , optionally at Block 320, a search can be performed based on HPLMN parameters. In an aspect, cell reselecting component 246, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, communicating component 240, priority determining component 242, cell measuring component 244, etc., can perform the search based on the HPLMN parameters. For example, the HPLMN of the UE 115 may also define parameters for performing IRAT searches for target cells. In this example, cell reselecting component 246 may also attempt this searching procedure to locate a more desirable target cell for the UE 115. In this regard, target cell searching in reselection can be performed on multiple other frequencies in an attempt to improve communications for the UE 115 when the UE 115 is configured with individual priorities that are not valid in a reselected or fallback RAT, as described above.

FIG. 4 is a block diagram of a MIMO communication system 400 including a base station 105 and a UE 115. The MIMO communication system 400 may illustrate aspects of the wireless communication system 100 described with reference to FIG. 1. The base station 105 may be an example of aspects of the base station 105 described with reference to FIGS. 1-2. The base station 105 may be equipped with

antennas

434 and 435, and the UE 115 may be equipped with

antennas

452 and 453. In the MIMO communication system 400, the base station 105 may be able to send data over multiple communication links at the same time. Each communication link may be called a “layer” and the “rank” of the communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system where base station 105 transmits two “layers, ” the rank of the communication link between the base station 105 and the UE 115 is two.

At the base station 105, a transmit (Tx) processor 420 may receive data from a data source. The transmit processor 420 may process the data. The transmit processor 420 may also generate control symbols or reference symbols. A transmit MIMO processor 430 may perform spatial processing (e.g., precoding) on data symbols, control symbols, or reference symbols, if applicable, and may provide output symbol streams to the transmit modulator/

demodulators

432 and 433. Each modulator/demodulator 432 through 433 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator/demodulator 432 through 433 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a DL signal. In one example, DL signals from modulator/

demodulators

432 and 433 may be transmitted via the

antennas

434 and 435, respectively.

The UE 115 may be an example of aspects of the UEs 115 described with reference to FIGS. 1-2. At the UE 115, the

UE antennas

452 and 453 may receive the DL signals from the base station 105 and may provide the received signals to the modulator/

demodulators

454 and 455, respectively. Each modulator/demodulator 454 through 455 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator 454 through 455 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 456 may obtain received symbols from the modulator/

demodulators

454 and 455, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive (Rx) processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, providing decoded data for the UE 115 to a data output, and provide decoded control information to a processor 480, or memory 482.

The processor 480 may in some cases execute stored instructions to instantiate a communicating component 240 (see e.g., FIGS. 1-2) .

On the uplink (UL) , at the UE 115, a transmit processor 464 may receive and process data from a data source. The transmit processor 464 may also generate reference symbols for a reference signal. The symbols from the transmit processor 464 may be precoded by a transmit MIMO processor 466 if applicable, further processed by the modulator/demodulators 454 and 455 (e.g., for SC-FDMA, etc. ) , and be transmitted to the base station 105 in accordance with the communication parameters received from the base station 105. At the base station 105, the UL signals from the UE 115 may be received by the

antennas

434 and 435, processed by the modulator/

demodulators

432 and 433, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438. The receive processor 438 may provide decoded data to a data output and to the processor 440 or memory 442.

The components of the UE 115 may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted modules may be a means for performing one or more functions related to operation of the MIMO communication system 400. Similarly, the components of the base station 105 may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted components may be a means for performing one or more functions related to operation of the MIMO communication system 400.

The above detailed description set forth above in connection with the appended drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. The term “example, ” when used in this description, means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a specially-programmed device, such as but not limited to a processor, a digital signal processor (DSP) , an ASIC, a FPGA or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A specially-programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially-programmed processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a non-transitory computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a specially programmed processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) .

Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for prioritizing frequency channels for measuring in reselection, comprising:

determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid;

adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities;

adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities; and

where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.
The method of claim 1, further comprising, where the reselection set of priorities does not include at least one frequency channel, searching for a target cell for reselection using one or more search parameters defined by a home public land mobile network.
The method of claim 1, wherein the list of individually prioritized frequency channels are specified to override the list of commonly prioritized frequency channels in determining frequency channels for searching target cells in reselection.
The method of claim 1, further comprising receiving the list of individually prioritized frequency channels in a radio resource control (RRC) message from a serving cell.
The method of claim 1, further comprising receiving the list of commonly prioritized frequency channels in a broadcast message from a cell of the radio access technology.
The method of claim 1, wherein the searching for the target cell comprises searching for the target cell having a different radio access technology.
The method of claim 1, further comprising:

discovering the target cell on the at least one frequency channel; and

performing, based on discovering the target cell, reselection to the target cell.
An apparatus for wireless communication, comprising:

a transceiver for communicating in a wireless network via one or more antennas;

a memory configured to store instructions; and

one or more processors communicatively coupled with the transceiver and the memory, wherein the one or more processors are configured to:

determine whether one or more frequency channels received in a list of individually prioritized frequency channels are valid;

add, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities;

add, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities; and

where the reselection set of priorities includes at least one frequency channel, search for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.
The apparatus of claim 8, wherein the one or more processors are further configured to, where the reselection set of priorities does not include at least one frequency channel, search for a target cell for reselection using one or more search parameters defined by a home public land mobile network.
The apparatus of claim 8, wherein the list of individually prioritized frequency channels are specified to override the list of commonly prioritized frequency channels in determining frequency channels for searching target cells in reselection.
The apparatus of claim 8, wherein the one or more processors are further configured to receive the list of individually prioritized frequency channels in a radio resource control (RRC) message from a serving cell.
The apparatus of claim 8, wherein the one or more processors are further configured to receive the list of commonly prioritized frequency channels in a broadcast message from a cell of the radio access technology.
The apparatus of claim 8, wherein the one or more processors are configured to search for the target cell having a different radio access technology.
The apparatus of claim 8, wherein the one or more processors are further configured to:

discover the target cell on the at least one frequency channel; and

perform, based on discovering the target cell, reselection to the target cell.
An apparatus for prioritizing frequency channels for measuring in reselection, comprising:

means for determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid;

means for adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities;

means for adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities; and

means for, where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.
The apparatus of claim 15, further comprising means for, where the reselection set of priorities does not include at least one frequency channel, searching for a target cell for reselection using one or more search parameters defined by a home public land mobile network.
The apparatus of claim 15, wherein the list of individually prioritized frequency channels are specified to override the list of commonly prioritized frequency channels in determining frequency channels for searching target cells in reselection.
The apparatus of claim 15, further comprising means for receiving the list of individually prioritized frequency channels in a radio resource control (RRC) message from a serving cell.
The apparatus of claim 15, further comprising means for receiving the list of commonly prioritized frequency channels in a broadcast message from a cell of the radio access technology.
The apparatus of claim 15, wherein the means for searching for the target cell searches for the target cell having a different radio access technology.
The apparatus of claim 15, further comprising:

means for discovering the target cell on the at least one frequency channel; and

means for performing, based on discovering the target cell, reselection to the target cell.
A computer-readable medium, comprising code executable by one or more processors for prioritizing frequency channels for measuring in reselection, the code comprising:

code for determining whether one or more frequency channels received in a list of individually prioritized frequency channels are valid;

code for adding, where the one or more frequency channels are determined to be valid, the one or more frequency channels to a reselection set of priorities;

code for adding, where the one or more frequency channels are determined not to be valid, one or more other frequency channels, received in a list of commonly prioritized frequency channels for a radio access technology, to the reselection set of priorities; and

code for, where the reselection set of priorities includes at least one frequency channel, searching for a target cell for reselection on the at least one frequency channel in the reselection set of priorities.
The computer-readable medium of claim 22, further comprising code for, where the reselection set of priorities does not include at least one frequency channel, searching for a target cell for reselection using one or more search parameters defined by a home public land mobile network.
The computer-readable medium of claim 22, wherein the list of individually prioritized frequency channels are specified to override the list of commonly prioritized frequency channels in determining frequency channels for searching target cells in reselection.
The computer-readable medium of claim 22, further comprising code for receiving the list of individually prioritized frequency channels in a radio resource control (RRC) message from a serving cell.
The computer-readable medium of claim 22, further comprising code for receiving the list of commonly prioritized frequency channels in a broadcast message from a cell of the radio access technology.
The computer-readable medium of claim 22, wherein the code for searching for the target cell searches for the target cell having a different radio access technology.
The computer-readable medium of claim 22, further comprising:

code for discovering the target cell on the at least one frequency channel; and

code for performing, based on discovering the target cell, reselection to the target cell.